Recently, microelectromechanical devices have been attracting attention and developed for practical use, in which a microelectromechanical system (MEMS) is formed on a main surface of a semiconductor substrate made of silicon wafer or other materials by application of processing techniques for forming fine wiring of elements in semiconductor integrated circuits and the like. Various microelectromechanical systems are being developed, and examples thereof include sensors such as accelerometers.
As a technique for sealing this microelectromechanical system, packaging techniques at wafer level have been intensely researched and developed. The packaging techniques are more advantageous than those using wire bonding, in that the package size can be reduced.
For example, Japanese Unexamined Patent Publication JP-A 2005-251898 discloses a microelectromechanical apparatus, comprising a first substrate that includes a microelectromechanical system, and a second substrate that is bonded so as to seal the microelectromechanical system, wherein a solder is used both to connect an electrode disposed on the first substrate and a wiring line disposed on the second substrate and to bond the first substrate and the second substrate.
However, in a case where a solder is used both as a connecting member that connects the electrode and the wiring line and as a sealing member that bonds the first substrate and the second substrate, there is the problem that an electrical short-circuit occurs due to spread of the solder that is melted by heat when the pitch, which is the distance between the connecting member and the sealing member, is small.